Protect it in your browser
- Open Protect PDF and drop in your PDF.
- Type a password twice.
- Click Protect PDF and download it.
The PDF is encrypted with AES-256 on your device. Neither the document nor the password is uploaded.
Choose a strong password
Encryption is only as strong as the password. Use at least 12 characters, or four random words. A password generator makes one for you.
Send the password separately
Do not put the password in the same email as the PDF. Send it by text message, say it on the phone, or agree on it in advance, so someone who gets hold of the email does not get both.
On a Mac with Preview
Open the PDF in Preview, choose File → Export, tick Encrypt (called Permissions in some versions) and set a password.
If you forget the password
There is no way to recover it: that is the point of encryption. Keep the original unprotected file somewhere safe, or store the password in a password manager.
Two kinds of PDF password
- An open password encrypts the file. Without it, the pages cannot be read at all. This is the kind Protect PDF sets.
- A permissions password asks reader programs to block printing, copying or editing, but anyone can still open and read the file, and many programs ignore the restrictions. It is a request, not a lock.
What a password does not do
Once someone has opened the file with the password, they can print it, take screenshots or save an unprotected copy. A password keeps the file safe in transit and in storage, not after you have shared the password.
Common problems
- The recipient cannot open it. AES-256 needs a reader from about 2008 (Acrobat 9) or later. Every current browser and PDF app can open it; very old office software may not.
- The password is rejected. Passwords are case-sensitive, and a phone keyboard may add a capital letter or a space at the start. Type it rather than pasting it.